This section provides background information related to the present disclosure which is not necessarily prior art.
An internal combustion engine “ICE” (e.g. gasoline or diesel) typically includes an exhaust device (e.g. a particulate matter filter and/or a catalytic converter) that includes a substrate having a plurality of channels through which exhaust gasses can flow.
Filter substrates (e.g. in a particulate matter filter) can filter particulate matter (e.g. soot) out of the exhaust gasses before the exhaust gasses are emitted to the atmosphere. Filter substrates are typically a ceramic (e.g. cordierite) block that is extruded to have a plurality of small, parallel passageways which have walls that are permeable to gasses while being configured to trap particulate matter.
Particulate matter can build up on these filter substrates, which can restrict exhaust flow and cause undesired back pressure. This buildup of particulate matter can be non-uniform throughout the filter substrate and can result in decreased fuel efficiency and power of the ICE. Buildup of particulate matter on the filter substrate can be reduced by increasing the temperature of the particulate matter to a light-off temperature in a process known as regeneration.
When regeneration is needed, an increased volume of fuel is typically delivered into the ICE's combustion chamber to cause the temperature of the exhaust gasses to increase. Once the temperature of the particulate matter reaches the light-off temperature, an exothermic reaction burns off the captured particulate matter. This method heats the entire filter substrate and can result in decreased fuel efficiency.
Similarly, catalytic substrates can reduce undesirable exhaust emissions (e.g. carbon monoxide “CO”, unburned hydrocarbons “HC”, nitrogen oxides “NOx”) by catalyzing chemical reactions to create more desirable emissions (e.g. carbon dioxide “CO2”, water “H2O”, nitrogen gas “N2”). Catalytic substrates are typically a ceramic (e.g. cordierite) block that is similarly extruded to have a plurality of small, parallel passageways. The ceramic block and passageways are typically coated with a material that catalyzes the chemical reactions necessary to achieve the more desirable emissions. In some applications, the catalytic substrate can also act as the particulate substrate. The coated catalytic substrate generally must be above a certain temperature (i.e. a light-off temperature) to efficiently catalyze the chemical reactions.
Typically, when the catalytic substrate is below the light-off temperature (e.g. after a cold start), an increased volume of fuel is delivered into the ICE's combustion chamber to cause the temperature of the exhaust gasses to increase. This method heats the entire catalytic substrate and can result in decreased fuel efficiency.